On Sun, 05 Oct 2014 01:46:03 +1000, Steven D'Aprano <steve+comp.lang.pyt...@pearwood.info> wrote:
>Seymore4Head wrote: > >> A little more: decimal_portion >> >> Write a function that takes two number parameters and returns a float >> that is the decimal portion of the result of dividing the first >> parameter by the second. (For example, if the parameters are 5 and 2, >> the result of 5/2 is 2.5, so the return value would be 0.5) >> >> http://imgur.com/a0Csi43 >> >> def decimal_portion(a,b): >> return float((b/a)-((b//a))) >> >> print (decimal_portion(5,2)) >> >> I get 0.4 and the answer is supposed to be 0.5. > >Hint: given arguments a=5, b=2, you want 5/2. What do you calculate? Look at >the order of the arguments a and b in the function def line, and in the >calculations you perform. > >Once you fix that, I can suggest a more efficient way of calculating the >answer: use the modulo operator % > >Given arguments 5 and 2, you want 0.5 == 1/2, and 5%2 returns 1. > >Given arguments 6 and 2, you want 0.0 == 0/2, and 6%2 returns 0. > >Given arguments 8 and 3, you want 0.6666... == 2/3, and 8%3 returns 2. > > >P.S. the usual name for this function is "fraction part", sometimes "fp". Yeah, I caught my mistake. Thanks for the suggestions. I was expecting a lesson in rounding errors, so I had ruled out the error was on my part. (Something I should never do) -- https://mail.python.org/mailman/listinfo/python-list
